Why pin 15?

M5Boost · Post by **M5Boost** » Thu Aug 03, 2006 8:46 pm

v3.0, msns-e, 60-2 wheel decoder, vr sensor, single coil with distributor.

I finally got a new MS unit and can power up, connect, and communicate with the ecu and my laptop.

I have no trigger signal showing in MT when cranking.
I see on the msns-e webpage that pin 15 is grounded. Why is this? Looking at the 3.0 schematics it looks as though pin 15 is connected to the other ground pins which are grounded. I haven't grounded pin 15 yet. Can someone please give me a reason why it needs to be grounded? I don't get it. I also need to shield my VR sensor wires. Haven't done that yet either. I figured even if they weren't shielded i should still get a signal, right? I'm planning on shielding them ASAP but im just trying to get this thing to fire up.

Thank you so much for your time and knowledge!
-Jesse

KB Motorsports
San Marcos, CA

Post by **jsmcortina** » Fri Aug 04, 2006 1:47 am

I drew that as an additional power ground. You can use any of the pins for ground, but when driving a coil as well make sure you add at least one more than standard.

James

M5Boost · Post by **M5Boost** » Fri Aug 04, 2006 6:53 pm

Would unshielded VR sensor wires solely cause no RPM signal at all?

M5Boost · Post by **M5Boost** » Sat Aug 05, 2006 11:31 am

Anyone know? thank you
-jesse
shielded wires are on order.

Post by **jsmcortina** » Sun Aug 06, 2006 1:25 pm

I doubt if unshielded wires would do that. I do not have shields on mine and it picks up tach fine. However the shielding will be useful once the engine is running to filter out spark noise.

James

redjetta · Post by **redjetta** » Tue Aug 08, 2006 10:45 am

Did you figure it out? I'm having the same problem.

http://www.msefi.com/viewtopic.php?t=21321

M5Boost · Post by **M5Boost** » Wed Aug 09, 2006 7:35 pm

No I didn't. When I scope my VR sensor it seemed it was giving less than 200mV at cranking. I'm still waiting on my shielded wire but i dont think that's my problem. I'm using the original VR sensor on the front of a BMW s38 motor. The sensor was only originally intended for diagnostic purposes (TDC trigger). The sensor is pretty small. It is about 1/2" wide and a little over an inch long. I assume the bigger the sensor, the greater the output??? I can't use an HEI module to try and get a tach signal because it is a 60-2 wheel. Too much frequency for an HEI unit right??? I'm going to try to mount up another VR sensor i have which is a little thicker and twice as long and see if i get anything. Would I NOT get a tach signal if I had it on trigger return instead of time based cranking??? I was SO excited to get my turbo M5 running nicely but this is depressing me. Does anyone have suggestions?
THANK YOU

Jon k · Post by **Jon k** » Thu Aug 10, 2006 8:10 am

M5Boost wrote:No I didn't. When I scope my VR sensor it seemed it was giving less than 200mV at cranking. I'm still waiting on my shielded wire but i dont think that's my problem. I'm using the original VR sensor on the front of a BMW s38 motor. The sensor was only originally intended for diagnostic purposes (TDC trigger). The sensor is pretty small. It is about 1/2" wide and a little over an inch long. I assume the bigger the sensor, the greater the output??? I can't use an HEI module to try and get a tach signal because it is a 60-2 wheel. Too much frequency for an HEI unit right??? I'm going to try to mount up another VR sensor i have which is a little thicker and twice as long and see if i get anything. Would I NOT get a tach signal if I had it on trigger return instead of time based cranking??? I was SO excited to get my turbo M5 running nicely but this is depressing me. Does anyone have suggestions?
THANK YOU

I am using the stock CPS from my M50 bmw motor (1992) and it works just fine. Check the polarity of the vr sensor wires you've got going. Also, I had to ground something on my harness I don't remember why but I think the harness I got from DIY had the VR leads over the wrong pins or something.

snillet · Post by **snillet** » Thu Aug 10, 2006 10:44 am

The bosch VR sensor on my engine is about the same size as the one you´re mentioning ....so i don´t think the size itself is an issue.

M5Boost · Post by **M5Boost** » Sat Aug 12, 2006 3:32 pm

OK, For everyone's information:

The diagnostic crank sensors used on the early BMW m30 and s38/m88 engines cannot be used to trigger MS. I originally scoped the output and had about 200 mV during cranking. Then, just today I removed the sensor to try another style. I noticed the original sensor didnt seem magnetic, eventhough I did have a visual wave pattern on a scope and it is definately not a hall sensor. So I used a different style sensor in there the engine fired right up. Very strange, is there another type of sensor which is not powered and creates a wave without a magnet? The magnet is probably very small or something. strange... THANK YOU to all who have tried to help. Especially Jsmcortina who seems to attempt to help EVERYONE!! Mucho appreciation to the hard work and dedication.
-Jesse

Megasquirt Support Forum (MSEXTRA)

Why pin 15?

Why pin 15?

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Re: .

YAY!! FIXED